Die rolled article and die rolling method



April 23, 1935. T. N. SLOAN 1,998,970

v DIE ROLLED ARTICLE AND DIE ROLLING METHOD Filed Aug. 51, 1931 2Sheets-Sheet 1 ,1 l N- M! T II THOMAS M SZOA/V T. N. SLOAN 1,998,970DIE-ROLLED ARTICLE AND DIE ROLLING METHOD I A ril 23, 192.5.

Filed Aug. -31, 1931 2 Sheets-Sheet 2 I gwvenioc rho/ms m 51 0A Nabhor/wag 5 Patented A a... 23,1935

PATENT OFFICE DIE ROLLED ARTICLE AND DIE ROLLING METHOD Thomas N. Sloan,Buffalo, N. Y., assignor to The Republic Steel Corp., Youngstown, Ohio,a corporation of New Jersey Application August 31, 1931, Serial No.560,299

19 Claims.

' This invention relates broadly to the are r die rolling and moreparticularly to die rolled, connected, flash-free forging blanks andanalogous articles having complex shapes, and to a and cheapen the costof production thereof by eliminating certain steps and attendantoperations heretofore considered essential in their manufacture. Y

Prior to this invention automobile front axles, cam-shafts and likearticles having large and small portions have been produced commerciallyby forging a rolled bar of uniform cross section into a blank suitablefor the forging die, in which the blank was then forged into an articleof the desired shape. This method, while slow and expensive, had beenthe most commercially practical method known in the art, althoughvarious efforts have been made to produce forging blanks for sucharticles by die rolling.

The earlier efforts to die roll such articles were directed toward theadaptation of the methods,

used in rolling hardware articles such as iron straps, tie rods, fishplates, etc. to the rolling of forging blanks, but in no instances, asfar as I know, have such ventures met with any commercial success andthey have beenabandoned. Their failure may be attributed to theinability to control longitudinal dimensions between portions of theblank and the relatively-great change in cross section or reduction.This inability was manifest in skidding or relative slippage between thebar and rolls. Following these attempts, efforts were made to adapt theflash principle of length control, such as is used in the die rolling ofcircular drive shafts for automobiles to the production of front axleforging blanks, but the flash produced as an important part of thatprocess had to be trimmed and/ or ground off, entailing considerableexpense and a separate operation which slowed down production, andmoreover, the flash or flash line was objectionable because it was oftenthe starting point in the development of cracks during the subsequentdiflicult or severe forging operations. To avoid flash, a two pass dierolling method was tried in which the metal was permitted to spreadfreely laterally in the first pass and was then rolled back into shapeby the second pass so that the blank was flat and of uniform dimensionbetween two opposite surfaces.

The two-pass method had several serious inherent disadvantages whichhave prevented its adoption on a commercial scale, among whichdisadvantages may be noted the following:

First, the heated leader bar cooled unequally during rolling and thelarge and small portions formed by the first roll pass were consequentlyoften altered materially in the second pass, particularly as regards thelength of the smaller sections or the spacing of the larger portionsalong the bar, and thus the center to center dimensions were notmaintained within the limits required by the final forging dies. Whilethe variable lengthening of parts of the bar might have been compensatedfor, in part, by more expensive diesink-'- ing operations, or cured bycutting where they occurred at the end of the blank, such lengthening asoccurred intermediate the ends of the blank could not be-so cured and ablank which does not meet the forging die requirements has to be dis- 1carded as scrap. I

Second, the variations in cross section along a rolled leader bar gavethe string of blanks a tendency to twist, tilt or camber after leavingthe first pass, and this tendency was exaggerated in the second passwhere the twisting or leaning of the tall narrow part of the blank wasemphasized and the symmetry thereof with respect to a central plane atright angles to the rolls was altered during flattening. Such distortedblanks, whenstruck in the forging dies tended to overfill some parts ofthe die and underfill'other parts, resulting in defective articles.

Briefly summarized, neither the flash method nor the two pass method hasbeen commercially successful for all purposes because of the forging andpossibly other inherent disadvantages.

vThe products typical of my invention may be briefly described as beinga string of connected, substantially identical, die rolled, flash freeforging blanks having substantially no lean, twist or tilt and havinggenerally rectangular portions of different heights and Widths spacedapart by predetermined distances and having predetermined crosssectional dimensions, all within close tolerance limits, that is, withinthe tolerances of dies used in the subsequent forging operation. By myimproved method and apparatus, I am enabled to produce such articles ona commercial scale and in a single roll pass.

Briefly stated my method may be carried out by the following steps;passing directly from the mill and between a single set of die rolls, arectangular metal leader bar having its greater dimension disposed atright angles to the surfaces of the rolls, this height or verticaldimension being slightly greater than the greatest depths of the groovesin the rolls and the width dimension being slightly less than the widthof the grooves; slightly reducing the height of certain portions of thebar, and greatly reducing the height of other portions of the bar withsimultaneous control of lateral spread, while preventing flash andcontrolling the locations of the larger and smaller portions along thebar within the close tolerances required by forging dies and in a mannerto form similar connected but severable blanks.

One form of apparatus embodying my invention consists of two cylindricalmembers, such as a set of die rolls, each mounted to rotate about itslongitudinal center line and each provided with complementary matrix"grooves shaped and dimensioned so that the rolls will grip the bar insuch manner as to prevent relative slippage and restrain the lateralflow of the metal and direct it longitudinally toward the unrolled partof the bar. The shallower parts of the said grooves are correlated, asto width and shape, with the diameter of the rolls or cylindricalmembers so as to influence or control the lateral spread of the bar; andas to length, with the rotational or peripheral speed of the rolls sothat elongation of the bar on the discharge side of the rolls will besubstantially prevented. Thus I have provided a method of and apparatusfor die rolling which enables me to produce in one operation arelatively great deformation or change in crosssectional contour of aleader bar with accurate center-to-center lengths between the deformedportions and without the use of flash as an aid in length control, andwith sections which may subsequently be forged into channel or beamsections with approximately equal filling of all parts of the forgingdie.

I have chosen to disclose my invention by setting forth in detailherein, as one embodiment of it, the method and apparatus I have used toform a heated leader bar into a string of forging blanks for front axlesfor an automobile.

In the drawings accompanying and forming a part of this specificationFigure 1 is a view in section and side elevation of apparatus embodyingthe present invention for die rolling a front axle forging blank,certain parts having been omitted.

Figure 2 is an end elevation taken on line 2- of Fig. 1.

Figure Bis an enlarged view of one of the rolls of Figure 1.

Figures 4 and 4a are respectively views in top plan and side elevationof a forging blank as produced by the die roll pass of Figure 1.

Figures 5a to 5d, inclusive, show cross sectional views taken on linesA, B, C and D of Figure 4a; and

Figure 6 is a perspective view showing a fragment of a leader bar dierolled by this invention into a string of connected front axle forgingblanks.

In Figures 1, 2 and 3, which show one form of die rolling deviceembodying my invention, i and 2 designate cylindrical rings keyed tomandrels 3 and 4, respectively, which are suitably mounted in bearings(not shown) to rotate about their centerlines and which are driven byany suitable means (also not shown). Each ring and its mandrel may beconsidered as a roll or member unit, but made in two parts forconvenience and cheapness in manufacture, upkeep and repair.

The rings l and 2 are mounted with their surfaces close together, aspace of about A" therebetween being suitable for a front axle forgingblank and suificient for adjustments to compensate for differences intemperatures of the heated leader bars.

Complementary grooves 5 and 6 in the faces of the rings l and 2 extendcircumferentially of the rings. These grooves are made up of'deep,narrow parts and shallower, wider parts and are long enough to form onecomplete front axle forging blank from a leader bar for each revolutionof the rings.

The deep, narrow parts I and 8 of the grooves 5 and 6 are of slightlyless depth than'the vertical height of the leader bar so that the latteris but slightly deformed therein, and are slightly wider than the bar sothatno flash is initially formed. Since there is very little reductionor deformation at these points, it will be seen that there is littledanger of inaccurate lengths due to roll slippage or skidding and forextrusion of metal into the formed bar during this phase of the rollingoperation. The shallower, wider parts 9 and ID of grooves 5 and 6 are ofconsiderably less depth than the. parts 1 and 8 and are much wider. Thedifference in depth between parts i and 8 and the parts 9 and I0 is theamount of draw or reduction in the smaller sections of the blank and itis this reduction that has heretofore rendered accurate and uniformdimensioning of this type of articles a diflicult problem.

In constructing the rolls I and 2 in accordance with my invention,several factors are taken into consideration and correlated, including(a) the dimensions and shape of the-grooves, (b) the relative locationof the deep and shallow parts of the grooves, (c) the diameter of therolls, ((1) the rotational or peripheralspeed of the rolls, and (e) thesize and shape of the leader bar. A

rolling temperature of around 1800 F. is suitable, although this mayvary over a relatively wide range without serious effects.

To. illustrate a course of procedure that may ,be followed in practicingmy invention, I preferably first lay out a pattern blank dimensioned toproduce a forging in accordance with given the standard usually beingaccepted as 1/64" for each inch of blank at a temperature of 1 800 F.

After thepattern blank has thus been suitably laid out, a forging blankis developed from it by taking into account any bends therein or othervariations from a straight line, for the forging blank is rolledstraight and later bent before being placed in the forging dies. Therolled blank must be capable of such bending and the like. Then matrixgrooves in the rolls are developed to form the forging blank. Indeveloping the grooves, I first locate the deep parts relative to eachother and make them large enough to give the metal necessary to formportions on the blank which will forge into the large'parts of the axle.Then the smaller parts of the groove are formed to give the requiredamount of draw or reduction of the leader bar for the smaller parts ofthe blank. The Walls which define the matrix grooves have an importantbearing on the results to be obtained. The side Walls arepreferablygiven a taper or clearance near the bottom of the grooves as at I2 (Fig.3) and from these points to the surface of the rolls they are preferablysubstantially straight sided and parallel. The width of the groove atthe parts 9 and II! or in the region where the greatest deformation ofthe bar takes place is such that the metal will spread against the wallsof the groove and fill the grooves but not overfill them to the extentthat flash will be formed on the sides of the'blank. A generallyrectangular cross-sectional shape with substantially parallel sides andoval-shaped top and bottom as shown in Figs. 5A to 5D, inclusive,facilitates such filling and flash prevention. I have found that thelateral spread or flow of the metal during the rolling operation may bereduced and controlled by making the bottom surfaces of the matrixgrooves in the die rolls rounded to form an article having rounded topand bottom surfaces as shown in Figures,5A, 5B, 5C and 5D. By thuscontrolling and restricting the lateral flow of the metal the matrixgrooves in the rolls will be just filled by the metal but not overfilledto cause extrusion of the metal into the space between the rolls and theforming of a fin or flash even when the leader bar is subject resultsobtained with grooves having rounded b'ottom surfaces are due to reasonsother than those given above. In conjunction with the foregoing, thereis subtracted from the depth of the groove the estimated amount of rollspring, so that the metal is firmly gripped in the matrix groove whenthe deformation action takes place. The substantially parallelside wallsof the groove greatly restrict the free flow of metal and cause it tofill the groove, any excess metal being given a tendency to flowlengthwise toward the unrolled part of the bar, the peripheral speed ofthe rolls influencing this latter action.

Figure 3 taken in conjunction with Figures 4, 4a and "5 illustrate asuitable matrix groove in one of the rolls. Considering the blank inFigures 4 and 4:1 as a forging blank, the actual dimensions of thegroove may be arrived at by adding a shrinkage allowance of about 1/64"per inch of the cold blank to the thickness of the blank, (that is, tothe sides presented to the observer in Figure 4a). From this sum issubtracted the estimated amount of roll spring and roll set. This givesthe correct groove depth, one-half of which is preferably in each roll.The width of the groove is substantially the same as that of the forgingblank plus shrinkage, (this width being from side to side of the blankpresented to the observer in Fig. 4). The relative spacing of thedeforming portions of the matrix groove and the substantiallyundeforming portions and the amount of draw therebetween issubstantially as indicated by the lines of projection 5A, 5B, 5C and 5Din Figs. 4 and 4a.

Preferably the diameter of the rolls is such that but one blank can beformed by a single rotation of the rolls, as experience has demonstratedthat such diameter co-ordinates satisfactorily with the width of theshallow portions of the groove to produce the proper lateral spread ofthe metal. It will be understood, however, that where the articles areso short as to make this impractical, more than one blank can be formedby a single rotation of the rolls.

As the speed of rotation of the rolls influences the, longitudinal andlateral flow of the metal, this speed' should be regulated with respectto the diameter of the rolls and the spacing and dimensions of thematrix portions. However, this speed may vary over a relatively widerange, in which longitudinal flow of the metal into the already formedpart of the blank has little or no tendency to take place. Suitablespeeds are from about 100 lineal feet per minute upwardly. As the speedincreases the lateral flow is decreased.

A satisfactory type of leader bar is one having a cross-sectionapproximately the shape of the deeper parts of the matrix groove butslightly greater in height, andslightly less in width, so that the barwill be reduced slightly thereby when rolled. In Figure 1, the leaderbar is designated at I3. This figure shows how a string of flash freeblanks is rolled direct from the leader bar in one'operation.

Figure 6 shows the string of connected blanks after the rollingoperation. The parts la8a are formed by the portions 1 and 8 of thematrix grooves and subsequently forged into the spring pads of the axle.The parts Sit-Illa, are formed by the portions 9 and ill of the groovesand are subsequently forged into the sections of the axle which liebetween the steering spindle swivel and the spring pads. The part 5a-6ais formed by the portions 5 and 6 of the matrix grooves, and thisportion of the string is severed at an intermediate point and eachadjacent end formed into a steering spindle swivel. The central channelor I-beam section 0' of the axle is formed by the portions 0 of thematrix grooves.

In practice, I pass a heated leader bar of the proper size and shapedirectly from the mill on.

edge between driven and matched rolls and 2 in grooves Band 6. The largeparts I and 8 of the grooves reduce the height of the leader barslightly without material lateral spread and without formation of flash,while the parts 9 and- ID draw the bar or reduce its height to anydesiredamount up to, forexample, about 40% or more, with coincidentlateral spread but still without flash. As this radical deformation ofthe bar begins, there would be, under the old unsuccessful attempts atrolling. a tendency toward slippage or skidding of the rolls on thebarwith consequent fatal results, unless flash was used to prevent suchaction. With my meth- 0d and apparatus, however, the bar holds to therolls due to the correlation of the several factors above mentioned anddeformation takes place in accurate spaced relation while simultaneouslythe metal is directed longitudinally and laterally, the longitudinalflow being controlled so as to merge into the bar during its formationwhile not altering the predetermined contour of the bar or length of theformed parts of the bar; and the lateral flow being restricted andcontrolled so astions relatively to prior methods of die rolling,

due to the fact that the side edges of the matrix grooves are notconstantly biting on the metal and being broken down thereby, actualexperience having shown a reduction of more than 80% in roll costs. Theblanks almost without exception roll true to specifications andrejections are reduced to a minimum.

Forging blanks and the like produced by my improved method difier intheir physical characteristics and particularly in the flow linearrangement of the material of the finished articles, from thoseproduced prior to my invention. The flow lines referred to above andhereinafter,

' both in the specification andclaims, may be 'dereference is madeherein particularly-to the longitudinal flow lines of the forging blankit will .be understood that flow lines would also appear on transversesections of an article where the forming operations have caused lateralspreading or flow of the metal.

Flow lines on my improved article may be observed by cutting alongitudinal section through the rolled blank and then polishing andetching the cut surface. As is well known to those skilled in the art,the flow line arrangement or structure of a forged metallic article hasan important bearing upon the strength and usefulness of the finished,article; Failure occurs more frequently in articles having cut or brokenflow lines than in those in which the flow lines smoothly follow thecontour of the article. In the Witherow type of blank, in which a flashis formed and thenremoved, the flow lines on planes through the flashare necessarily cut when the flash is removed. 'I'his results in'a' zoneof weakness in the finished article and an undesirable structure. In theWitherow type of blank, or any blank formed with flash, the longitudinalflow lines on the plane of the flash are cut at each lateral enlargementor projection on the blank and even though the articlebe reforged theoriginal cut flow line structure will persist and produce an inferiorarticle as compared with applicants product in which the flow lines are'all substantially continuous throughout the length of the blank. In myblanks, which are formed without flash,

, the flow lines, as seen on any plane, either longitudinal ortransverse, through a blank or string of blanks follow the contour ofthe blank and at no point are they cut or broken. Thus, my blanks havean ideal flow line arrangement.

While I have shown and described rolls which are set about A" apart. Ido not limit myself to any such set, nor to grooves which approximatehalf the thickness of the rolled blank. With many articles, the roll setmay be increased considerably above this example with consequentdecrease in depth of the grooves in the rolls. However, there is a welldefined limit to the maximum of the set or space between the rolls. Theroll set should not be so great that effective control of the lateraldimensions of the small sections is lost. When excess flash is formed onthe small sections during forging, the set is too great. In other words,efiective lateral control of the small sections is maintained when noexcessive forging flash is formed during forging of those sections.

It will be understood from the foregoing disclosure of a preferredmethod of, and apparatus, for practicing my invention, that I have beenable to produce from a long leader bar of uniform rectangular crosssection, a string of connected but severable, substantially identical,complex, forging blanks, and that each blank is free from flash andsevered flow lines with large generally rectangular sections, spacedapart from each other by smaller generally rectangular sections thelengths of some of which are longer than those of others, and that thedimensions of these large and small sections are accurate within thetolerances of a forging die in which the article is to be forged. Itwill also be observed that the large sections have their long crossdimensions 'in a plane substantially at right angles to the long crossaxis of the smaller sections, that is, that the smaller sections projectlaterally beyond the sides of the large sections. The small sections aresubstantially symmetrical about a central plane therethru which isperpendicular to the narrow edges of the bar, and also about a centralplane which is perpendicular to the narrow edges of the small sections.The

trailing ends of the long small sections are of sufficient size so thatthese parts of the blan fill the forging die.

In the preferred apparatus, the rolls are positioned very close to eachother. The groove for the blank is formed partly in each rollandpreferably equally in each roll. The rolls are preferably matched,that is, they. are positioned with their grooves relative to each other,sothat the resulting blank will have the shape and dimensionsdesired. k

In the-preferred method, the long heated bar enters on edge between. therolls and is propelled by the driven rolls. The rolls grip the narrow.edge of the bar, squeezing it down some-' what without materialwidening and the shallower parts of the groove squeeze the bar downfurther and 'flatten it, causing lateral flow of the metal intoengagement with the side walls of the groove and also .causinglengthwise flow of the metal into unrolle'd parts thereof, that is,

in a direction opposite to that of the travel of the bar. In this mannerthe dimensions and shape of the smaller sections arecontrolled.

The term finish as used in conjunction with the expression forging blankappearing in the desire to secure by Letters Patent is defined by whatis claimed.

What is claimed is- 1. The method of die rolling blanks having large andsmall sections accurately spaced from each other from leader bars in asingle roll pass which lincludes passing a heated metal leader barbetween similarly grooved rollers constituting a single die roll passand having a maximum groove depth slightly less than the maximumcorresponding dimension of the bar, maintaining the peripheral speed ofthe rolls above the speed at which longitudinal flow of the leader barinto previously rolled portions thereof may take place, and controllingand directing the lateral flow of the metal of the bar by confining themetal in matrix grooves having curved bottom surfaces in a manner toprevent the formation of flash and to maintain predetermined spacingsbetween large and small sections of the blank formed by correspondingportions of the grooves in the rolls.

2. In the method of die rollin'g forging blanks having large and smallportions accurately spaced from each other from heated leader bars ofuniform cross-section in a single roll pass, the steps of passing aleader bar of uniform cross-section between a pair of die rolls havingcomplementary grooves formed in the surfaces thereof and of a maximumdepth slightly less than the maximum corresponding dimension of the barwith portions of said grooves varying in cross-sectional size and. shapeto produce a plurality of similar articles having differentcross-sectional sizes and shapes at different points, compensating forroll spring during the rolling operation on sections of great reductionto augment the gripping action of the rolls on the bar, controlling thelongitudinal and lateral flow of the metal of the bar in a manner toprevent the formation of flash and elongation of previously formedsections of great reduction, and finally'severing the string of blanksinto separate individual blanks.

3. A method of forming metal articles, comprising passing a heatedleader between a single pass of die rolls adapted to form a string ofconnected blanks, forming accurately spaced large and small portionsalong the string adapted for forging, directing and 'controlling theflow of metal of the leader to prevent formation of flash integral withthe blanks and the elongation of previously formed portions of greatreduction, separating the blanks, and thereafter heating and forging atleast certain portions of the blanks.

4. The method of forming metal articles which includes the steps ofpassing a heated metal leader bar on edge between a single pair ofrolls, shaping the bar by said rolls into a plurality of substantiallyidentical, integrally connected forging blanks, each blank having largeand small generally rectangular sections accurately spaced from eachother with the large sections extending beyond the surface plane of theadjacent small sections, directing the flow of metal of the bar duringrolling longitudinally of the bar'between surfaces of the rolls whilepreventing the formation of flash or fins on the sides thereof and theelongation of previously formed sections of great reduction, andsevering the rolled bar to separate the blanks.

5. The method of forming metal articles which includes the steps ofpassing a substantially rectangular heated metal leader bar on edgebetween a single pair of rolls, shaping the bar into a plurality ofsubstantially identical, integrally connected forging blanks, each blankhaving large and small generally rectangular sections accurately spacedfrom each other, with each of the large sections being narrower in onedirection and thicker in another direction than the adjacent smallsections and projecting beyond one side of the adjacent small sections,by compressing the bar into recesses in the rolls while directing andcontrolling the metal of the bar between substantially parallel surfacesof the rolls so as to form uninterrupted longitudinal lines of flowduring rolling while preventing the formation of flash or fins thereonand the elongation of previously formed sections of great reduction, andsevering the rolled bar to separate the blanks.

6. The method of die rolling flash-free metal forging blanks havinglarge and small sections spaced from each other therealong whichincludes the steps of passing a heated metal leader bar on edge betweena pair of rolls in grooves having large and small sections, the maximumdepth of the grooves being slightly less than the maximum correspondingdimension of the bar, maintaining the peripheral speed of the rollsabove the speed at which longitudinal flow of the bar into previouslyrolled porti ns thereof may take place, controlling and directing theflow of the metal along unbroken longitudinal lines while preventingformation of flash or fin by confining the bar in the grooves certainportions of which have curved bottom surfaces and substantially straightsides.

7. The method of die rolling flash-free metal forging blanks havinglarge and small sections accurately spaced from each other, whichincludes the steps of passing a substantially 'rectangular leader bar ofsubstantially uniform cross-section on edge between a pair of rolls,slightly reducing the height of the bar and creating longitudinal flowlines therein by compressing it between the bottoms of circumferentiallyextending depressions in the rolls to form large substantiallyrectangular longitudinally spaced sections on the bar, greatly reducingthe height of the bar between the large sections and formingsubstantially rectangular sections of less height and greater width thanthe large sections while continuing the flow lines and withoutformingfins or flash by compressing it between roll surfaces closer togetherthan said spaced depressions, maintaining the peripheral speed of therollsabove the speed at which longitudinal flow of the bar intopreviously rolled sections thereof will take place, and severing therolled .u

bar to separate the blanks from each other.

8. The method of die rollinglarge, complex, metal forging blanks such asautomobile front axles, internal combustion crank and cam shafts, andthe like, which includes the steps of passing a heated, rectangular,metal leader bar on edge between a pair of die rolls, slightly reducingthe distance between the edges of the bar at places spaced therealongwithout material lateral or lengthwise flow of the metal to form largegenerally rectangular sections, greatly'reducing the distance betweenthe edge surfaces at other places along the bar with coincident flow ofthe metal laterally and lengthwise of the bar to form smaller sectionsbetween the large sections, limiting the extent of the lateral flowwhile preventing flash formation thereby making the smaller sectionsgenerally rectangular cross section,.and causing the lengthwise flow to'take place in a direction opposite to that of the movement of the bar,thereby controlling the length of the smaller sections.

9. The method of die rolling large, complex. metal forging blanks suchas automobile front axles, internal combustion crank and cam shafts, andthe like, which includes the steps of passing a heated, rectangular,metal leader bar on edge between a pair of die rolls, slightlyreducing'the distance between the edges of the bar at places spacedtherealong without material lateral or lengthwise flow of the -metal toform large generally rectangular sections, greatly reducing the distancebetween the edge surfaces at other places along the bar with coincidentflow of the metal laterally and lengthwise of the bar to form smallersections between the large sections, restraining lateral flow of themetal when the metal has reached predetermined points beyond the sidesof the largesections while preventing flash formation, thereby makingthe smaller sections generally rectangular cross section, and causingthe lengthwise flow to take place in a direction opposite to that of themovement of the bar, thereby controlling the length of the smallersections.

10. The method of die rolling large, complex, metal forging blanks, suchas automobile front axles, internal combustion engine crank shafts, camshafts and thelike, which includes the steps of gripping opposite edgesurfaces of a heated, metal leader bar of substantially uniform,rectangular cross section between opposed surfaces of a single pair ofdie rolls, driving the rolls to propel the bar endwise therebetween,slightly reducing the distance between said edge at a plurality ofplaces spaced along the bar to form large, generally rectangularsections, considerably reducing the distance betwe:n said edge surfacesand simultaneously widening the bar at other places to form smaller,generally rectangular sections, preventing the formation of flash alongthe smaller sections and controlling the dimensions of the smallersections within the forging die tolerances by forcing portions of theadjacent side surfaces of the bar laterally against roll surfaces,directing flow of the metal lengthwise of the bar into rolled partsthereof, and severing the thus rolled bar into a plurality of forgingblanks, each having a plurality of said large and small sections.

ll. The method of die roiling large, complex, metal forging blanks suchas automobile front axles, internal combustion engine crank and camshafts, and the like,,which includes the steps of driving a pair of dierolls having a die groove and thereby axially moving a heated, metalleader bar of substantially uniform rectangular cross section on edge insaid groove between said rolls, slightly reducing the distance betweenopposite edge surfaces of the bar at places spaced along the bar to formgenerally rectangular large sections, greatly reducing the distancebetween said edge surfaces and simultaneously increasing considerablythe width of the bar at a plurality of places along the bar to formsmaller sections between said large sections, limiting lateral flow ofthe metal in the small sections and preventing flash formation byconfining portions of the side surfaces of the metal in the groove togive said sections a generally rectangular shape, controlling thelengths of the small sections within forging die tolerances by drivingthe rolls at such a speed that the metal will flow lengthwise of the barin a direction opposite to the direction of travel of the bar, andsevering the thusrolled bar into forging blanks, each having a pluralityof large and small sections.

12. The method of die rolling large, complex, metal forging blanks suchas automobile front axles, internal combustion engine crank and camshafts, and the like, which includes the steps of driving a pair ofmatched, similarly grooved, die rolls and thereby axially moving aheated, metal leader bar of substantially uniform rectangular crosssection on edge between said rolls in said grooves, slightly reducingthe distance between the edge surfaces with simultaneous increase in thewidth of the bar and lengthwise flow of the metal at a plurality ofplaces along the bar to form smaller sections between said largesections, limiting the lateral flow of the metal and preventing flashformation on the smaller sections and giving them a generallyrectangular cross sectional shape, by confining substantially the entireside surfaces of the metal of the smaller sections by the groove sidewalls, driving the rolls at such a speed that the direction oflengthwise flow of the metal will be opposite to the direction of travelof the bar thereby controlling the length of said small sections withinthe forging die tolerances and severing the thus rolled bar into forgingblanks, each having a plurality of large and small sections.

13. The method of die rolling large, complex, metal forging blanks suchas automobile front axlis, internal combustion engine crank and camshafts, and the like, which includes the steps of moving a heated, metalleader bar of substantially uniform, rectangular cross section axiallyon edge into engagement between a pair of grooved die rolls, drivingsaid rolls and thereby propelling the bar therebetween, slightlyreducing the distance between the edge surfaces of the bar at aplurality of places spaced along the bar to form generally rectangularlarge sections, greatly reducing the distance between the edge surfacesat a plurality of places along the bar with coincident flow of the metalto form smaller sections joining the larger sections to each other,limiting lateral flow of the metal and preventing flash formation on thesmall sections thereby giving the smaller sections a generallyrectangular cross sectional shape, driving the rolls at such a speedthat the lengthwise flowof the metal will take place in a directionopposite to that of the travel of the bar thereby controlling thelengths of said smaller sections, and severing the thus rolled bar intoforging blanks, each having a plurality of said large and smallsections,

14. A string of substantially identical, complex 4 smaller sectionsbeing substantially symmetrical with respect to a. central planetherethru perpendicular to the narrow edges of the bar, and projectingbeyond the sidesof the larger sections.

16. A die rolled, complex finished, metal forging blank free from flashand severed flow lines and having large generally rectangular sectionsand smaller generally rectangular sections therebetween, certain of saidsmaller sections being relatively long. axially and projecting laterallybeyond the sides of the large sections, the said large and smallsections and blank having dimensions which are accurate within theforging die tolerances for the blank.

17. A die rolled, complex finished, metal forging blank having sectionswhich are large and generally rectangular in cross section and which arespaced from each other by sections which. are generally rectangular butsmaller in cross section, the side surfaces of the larger sections lyingin planes different from those of the side surfaces of the smallersections the dimensions of said sections and blank being within thetolerances of a forging die therefor, said blank being free from flashand the severed flow lines, lean and twist, and having thecharacteristics of a blank which has been made by passing a heated baron edge between a single pair of driven, grooved, die rolls. reducingthe distance between the edge surfaces more in certain places thanothers along the bar and causing metal at the greatly reduced places toflow lengthwise of the bar toward unrolled parts of the bar.

blank being within the tolerances of a forging die for the desiredarticle, each blank being free from flash, severed flow lines, lean andtwist, and having the characteristics of a blank which has been made bypassing a heated bar on edge between a single pair of die rolls;alternately reducing the distance between the edges of the bar slightlyand greatly, confining the sides of the greatly reduced parts beyond thesides of the large sections and causing the metal at such parts to flowlengthwise of the bar toward unrolled parts thereof.

19. A. die rolled, complex finished, metal forg-' sections lying inplanes different from those of the side surfaces of the smaller sectionsthe dimensions of said sections and blank being within the tolerances ofa forging die. therefor, said blank being substantially free from flash,severed flow lines, lean twist, and underfilling at the trailing endsofthe longer small sections, said blank having the characteristics of ablank which has been made by passing a heated bar on edge in anapproximately surrounding groove between a single pair pf driven dierolls with alternate large and small reductions of the distance betweenthe edge surfaces and coincident restrained lateral, and also lengthwiseflow of the metal at the places of large reduction toward unrolled partsof the bar.

THOMAS N. SLOAN.

